Valve timing adjusting apparatus

ABSTRACT

A valve timing adjusting apparatus for an internal combustion engine having a bearing includes a camshaft, a housing, a vane rotor, a control valve, and a fastening member. The fastening member is mounted on an axial end portion of the camshaft on a side of the vane rotor opposite from the bearing. The vane rotor is coaxially fastened to the camshaft between the fastening member and a step portion, which is provided to the camshaft on a side of the bearing. A sleeve of the control valve is coaxially received in an axial hole of the camshaft, which opens at an end surface of the end portion of the camshaft. Each of the advance output port and the retard output port is communicated with a corresponding one of the advance chamber and the retard chamber through the camshaft.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2007-315175 filed on Dec. 5, 2007.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a valve timing adjusting apparatus that adjusts valve timing of a valve that is opened and closed by a camshaft driven by a torque transmitted from a crankshaft in an internal combustion engine.

2. Description of Related Art

Conventionally, a widely-used fluid driven valve timing adjusting apparatus includes a housing, which is rotatable with a crankshaft, and a vane rotor, which is rotatable with a camshaft. In general, in the above valve timing adjusting apparatus, the vane rotor defines an advance chamber and a retard chamber in the housing, and working fluid is supplied to the above advance chamber or the retard chamber to rotate the vane rotor relative to the housing in an advance direction or in a retard direction. As a result, an engine phase of the camshaft relative to the crankshaft for determining the valve timing, is adjusted.

For example, in apparatuses described in JP-A-2006-63835 and JP-A-2004-340142, a control valve, which has a spool and a sleeve that slidably receives the spool, controls supply of working fluid into an advance chamber and a retard chamber. Specifically, the sleeve of the above control valve is provided with an input port, an advance output port, and a retard output port. Working fluid is inputted into the sleeve through the input port. Working fluid is outputted to the advance chamber through the advance output port, and working fluid is outputted to the retard chamber through the retard output port. The control valve displaces the spool to control communication between the input port and the advance output port or the retard output port.

In the apparatus of JP-A-2006-63835, the control valve is provided at a position different from the housing and from the vane rotor. In contrast, in the apparatus of JP-A-2004-340142, a vane rotor is fastened to an end portion of the camshaft, and a sleeve of a control valve, which is fixedly or stationarily provided on a side of the vane rotor opposite from the above end portion, is coaxially received in an axial hole of the vane rotor. Due to the above, a space required for mounting the apparatus having the control valve is reduced in size.

However, in the apparatus of JP-A-2004-340142, a length of the axial hole, which is provided to the vane rotor, is inevitably restricted by a specification of the apparatus, such as a thickness of the vane rotor. As a result, a length of the sleeve that is coaxially received in the axial hole is restricted. The above restriction or limitation may be a bottleneck disadvantageously in the attempt to secure a length of a sealing part for sealing between slide boundary surfaces of the sleeve and the spool in order to improve control responsivity of control valve and to adjust responsivity of valve timing. Thus, the above restriction is not preferable. Also, in the apparatus of JP-A-2004-340142, a first drain port is provided to discharge working fluid in the advance chamber therefrom, and a second drain port is provided to discharge working fluid in the retard chamber therefrom. The first and second drain ports are required to be communicated with the end portion of the camshaft, and thereby the sleeve may be increased in size and may have a complex configuration.

SUMMARY OF THE INVENTION

The present invention is made in view of the above disadvantages. Thus, it is an objective of the present invention to address at least one of the above disadvantages.

To achieve the objective of the present invention, there is provided a valve timing adjusting apparatus for an internal combustion engine having a bearing, wherein the valve timing adjusting apparatus adjusts valve timing of a valve based on torque transmitted from a crankshaft, and wherein the valve timing adjusting apparatus includes a camshaft, a housing, a vane rotor, and a control valve. The camshaft is supported by the bearing of the internal combustion engine. The camshaft opens and closes the valve based on the torque transmitted from the crankshaft. The camshaft has an end portion that extends in an axial direction from the bearing. The camshaft includes a step portion on a side of the bearing toward the end portion of the camshaft. The camshaft defines an axial hole therein that opens at an end surface of the end portion of the camshaft. The housing is rotatable synchronously with the crankshaft. The vane rotor is rotatable synchronously with the camshaft, which extends through the vane rotor. The vane rotor defines an advance chamber and a retard chamber in the housing. The vane rotor is rotatable relative to the housing in an advance direction when working fluid is supplied to the advance chamber. The vane rotor is rotatable relative to the housing in a retard direction when working fluid is supplied to the retard chamber. The control valve is received in the axial hole of the camshaft and includes a spool and a sleeve. The spool is slidably received in the sleeve. The sleeve is coaxially received in the axial hole and is stationarily provided. The sleeve includes an input port, an advance output port, and a retard output port. Working fluid flows through the input port into the sleeve. Working fluid flows through the advance output port into the advance chamber. Working fluid flows through the retard output port into the retard chamber. The control valve displaces the spool to control communication between the input port and the advance output port and to control communication between the input port and the retard output port. The fastening member is mounted on the end portion of the camshaft on a side of the vane rotor opposite from the bearing and the step portion. The vane rotor is coaxially fastened to the camshaft in a state, where the vane rotor is held between the fastening member and the step portion. Working fluid flows into the input port through the camshaft. Each of the advance output port and the retard output port is communicated with a corresponding one of the advance chamber and the retard chamber through the camshaft.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:

FIG. 1 is a configuration diagram illustrating a valve timing adjusting apparatus according to a first embodiment of the present invention and is a cross-sectional view along line I-I in FIG. 3;

FIG. 2 is a configuration diagram of a cross-sectional view taken along line II-II in FIG. 1;

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1;

FIG. 4 is a partial cross-sectional view illustrating an enlarged part of the valve timing adjusting apparatus according to the first embodiment of the present invention;

FIG. 5 is a configuration diagram illustrating the valve timing adjusting apparatus of the first embodiment in an operational state different from FIG. 1 and is a cross-sectional view taken along line V-V in FIG. 6;

FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5;

FIG. 7 is a partial cross-sectional view illustrating an enlarged part of the valve timing adjusting apparatus in an operational state different from FIG. 4;

FIG. 8 is a partial cross-sectional view illustrating an enlarged part of the valve timing adjusting apparatus in an operational state different from FIGS. 4, 7;

FIG. 9 is a configuration diagram of a cross-sectional view in an operational state different from FIG. 2;

FIG. 10 is a partial cross-sectional view illustrating an enlarged part of a valve timing adjusting apparatus according to a second embodiment of the present invention; and

FIG. 11 is a partial cross-sectional view illustrating an enlarged part of the valve timing adjusting apparatus in an operational state different from FIG. 10.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will be described with multiple embodiments with reference to accompanying drawings. In each of the embodiments, a corresponding component is indicated by the same numeral, and thereby overlapped explanation will be omitted.

First Embodiment

FIGS. 1, 2, 9 show examples, in which a valve timing adjusting apparatus 1 of the first embodiment of the present invention is applied to an internal combustion engine of a vehicle. The valve timing adjusting apparatus 1 is a fluid operated apparatus that employs hydraulic oil serving as “working fluid”, and is capable of adjusting valve timing of an intake valve that serves as a “valve”.

(Basic Configuration)

A basic configuration of the present embodiment will be described. The valve timing adjusting apparatus 1 includes a drive unit 10 and a control unit 30. The drive unit 10 is provided in a driving force transmission system and is driven by hydraulic oil. The driving force transmission system transmits a driving force of a crankshaft (not shown) of an internal combustion engine to a camshaft 2 of the internal combustion engine. The control unit 30 controls supply of hydraulic oil to the drive unit 10.

(Drive Portion)

The drive unit 10 includes a housing 11 and a vane rotor 14, and the housing 11 has a shoe housing 12 and a sprocket 13.

The shoe housing 12 includes a tubular portion 12 a and multiple shoes 12 b, 12 c, 12 d. The tubular portion 12 a has a hollow cylindrical shape with a bottom, and each of the shoes 12 b, 12 c, 12 d serves as a partitioning portion.

The shoes 12 b to 12 d are circumferentially arranged one after another at generally equal intervals on the tubular portion 12 a and radially inwardly project from the tubular portion 12 a. Each of the shoes 12 b to 12 d has a protrusion end surface that has an arcuate-shaped recess when taken along a plane perpendicular to an axial direction of the housing 11. In the above, the arc-shaped recess is formed radially outwardly. The vane rotor 14 has a hub portion 14 a, and the hub portion 14 a has a radially outer surface that faces the protrusion end surfaces of the shoes 12 b to 12 d with slight clearances therebetween. The vane rotor 14 is provided with chip sealing parts 15 on the hub portion 14 a, and each of the chip sealing parts 15 slides on the corresponding protrusion end surface of the shoes 12 b to 12 d. Also, multiple receiving chambers 50 are defined between the adjacent shoes of the shoes 12 b to 12 d that are arranged circumferentially or in a rotational direction.

The sprocket 13 has a circular ring plate shape, and is mounted on an opening end side of the tubular portion 12 a such that the sprocket 13 is coaxial with the tubular portion 12 a. The sprocket 13 is connected or linked with a crankshaft via a timing chain (not shown). Due to the above, during an operation of the internal combustion engine, a driving force is transmitted from the crankshaft to the sprocket 13 such that the housing 11 rotates in a clockwise direction in FIG. 2 together with the crankshaft.

The vane rotor 14 is coaxially received in the housing 11, and the vane rotor 14 is provided between a bottom wall surface of the tubular portion 12 a and an internal wall surface of the sprocket 13. One of axial end surfaces of the vane rotor 14 and one of the bottom and internal wall surfaces defines a slight clearance therebetween, and the other one of the axial end surfaces slidably contacts the other one of the bottom and internal wall surfaces. The vane rotor 14 includes the hub portion 14 a, which has a cylindrical column shape, and multiple vanes 14 b, 14 c, 14 d.

The hub portion 14 a is coaxially bonded to the camshaft 2. Thus, the vane rotor 14 rotates in the clockwise direction in FIG. 2 together with the camshaft 2, and rotates relative to the housing 11.

Each of the vanes 14 b to 14 d is arranged in the rotational direction one after another in equal intervals along the hub portion 14 a, and radially outwardly projects from the hub portion 14 a. Each vane 14 b to 14 d is received fluctuantly or movably in a corresponding receiving chamber 50. Each of the vanes 14 b to 14 d has a radial end surface, which radially outwardly protrudes from the hub portion 14 a to have an arcuate shape, and which faces the inner peripheral surface of the tubular portion 12 a with a slight clearance therebetween. The chip sealing part 15, which is provided to each of the vanes 14 b to 14 d, slides on the tubular portion 12 a.

Each of the vanes 14 b to 14 d divides the corresponding receiving chamber 50 into two chambers that are arranged one after another in the rotational direction such that each of the vanes 14 b to 14 d and the housing 11 define an advance chamber and a retard chamber serving as fluid chambers. Specifically, the shoe 12 b and the vane 14 b define an advance chamber 52 therebetween, the shoe 12 c and the vane 14 c define an advance chamber 53 therebetween, and the shoe 12 d and the vane 14 d define an advance chamber 54 therebetween. Also, the shoe 12 c and the vane 14 b define a retard chamber 56 therebetween, the shoe 12 d and the vane 14 c define a retard chamber 57 therebetween, and the shoe 12 b and the vane 14 d define a retard chamber 58 therebetween.

The vane 14 b receives a lock pin 26. The lock pin 26 is displaced by a restoring force of a compression coil spring 28 and is fitted with a fitting hole 27 provided at the bottom wall portion of the tubular portion 12 a such that the vane rotor 14 is locked on the housing 11. In contrast, when the lock pin 26 is applied with pressure of hydraulic oil supplied from one of the advance chamber 52 and the retard chamber 56, which are provided on both sides of the vane 14 b, the lock pin 26 is released from or disengaged from the fitting hole 27 such that the vane rotor 14 is unlocked from the housing 11.

As above, in the drive unit 10, when the lock pin 26 is fitted into the fitting hole 27 due to the decrease in pressure of hydraulic oil, the vane rotor 14 is limited from rotating relative to the housing 11.

In contrast, in the drive unit 10, when the lock pin 26 is released from the fitting hole 27 due to the increase in pressure of hydraulic oil, supply of hydraulic oil to the advance chambers 52 to 54 and discharge of hydraulic oil from the retard chambers 56 to 58 cause the vane rotor 14 to rotate relative to the housing 11 in the advance direction. Thus, an engine phase, which corresponds to a phase relationship of the camshaft 2 relative to the crankshaft, is changed in the advance direction. As a result, in the above case, valve timing is advanced. Also, when the lock pin 26 is released from or is taken out of the fitting hole 27, in the drive unit 10, supply of hydraulic oil to the retard chambers 56 to 58 and discharge of hydraulic oil from the advance chambers 52 to 54 cause the vane rotor 14 to rotate relative to the housing 11 in the retard direction. As a result, the engine phase is changed in the retard direction. Thus, in the above case, valve timing is retarded.

(Controller)

As shown in FIG. 2, in the control unit 30, advance passages 72, 73, 74 are communicated with the advance chambers 52, 53, 54, respectively, and retard passages 76, 77, 78 are communicated with the retard chambers 56, 57, 58, respectively.

An input passage 80 is provided to be communicated with a discharge port of a pump 4 serving as a fluid supply source, and drain passages 82, 83 (first and second drain passages) are provided to discharge hydraulic oil to an oil pan 5 provided on an inlet port side of the pump 4. Thus, the pump 4 compresses hydraulic oil pumped from the oil pan 5 to discharge the compressed oil to the input passage 80. In the above, the pump 4 of the present embodiment is a mechanical pump driven by the crankshaft, and thereby hydraulic oil is continuously supplied to the input passage 80 during the operation of the internal combustion engine.

A control valve 100 is a solenoid spool valve that employs a restoring force, which is generated by an electromagnetic driving force of a solenoid portion 120, to actuate a spool. In the above, the control valve 100 is provided with an input port 112, an advance output port 114, a retard output port 116, and first and second drain ports 118, 119. The input port 112 is communicated with the input passage 80 and receives hydraulic oil from the pump 4. The advance output port 114 is communicated with the advance passages 72 to 74 and outputs hydraulic oil. The retard output port 116 is communicated with the retard passages 76 to 78 and outputs hydraulic oil. The drain ports 118, 119 are communicated with drain passages 82, 83, respectively, and discharges hydraulic oil toward the oil pan 5. As a result, the control valve 100 is actuated in response to an energization of the solenoid portion 120, and controls communication between (a) each of the input port 112 and the first and second drain ports 118, 119 and (b) the corresponding one of the advance output port 114 and the retard output port 116.

A control circuit 150 includes, for example, a microcomputer, and is electrically connected with the solenoid portion 120 of the control valve 100. The control circuit 150 controls an operation of the control valve 100 by energizing the solenoid portion 120, and controls an operation of the internal combustion engine.

As above, in the control unit 30, when the control circuit 150 controls the operation of the control valve 100 to provide communication between the input port 112 and the advance output port 114 and to provide communication between the second drain port 119 and the retard output port 116, the discharge oil from the pump 4 is outputted to the advance chambers 52 to 54. Because hydraulic oil in the retard chambers 56 to 58 is discharged to the oil pan 5, the vane rotor 14 rotates relative to the housing 11 in the advance direction as shown in FIG. 9. Also, in the control unit 30, when the control valve 100 controls the operation of the control valve 100 to provide communication between the input port 112 and the retard output port 116 and to provide communication between the first drain port 118 and the advance output port 114, discharge oil of the pump 4 is outputted to the retard chambers 56 to 58, and hydraulic oil in the advance chambers 52 to 54 is discharged to the oil pan 5. Thereby, the vane rotor 14 rotates relative to the housing 11 in the retard direction as shown in FIG. 2.

(Characteristic Configuration)

Characteristic configuration of the present embodiment will be detailed below.

As shown in FIG. 1, the camshaft 2, which is made of a metal shaft, is rotatably supported by a bearing 161 of a metallic engine head 160 of the internal combustion engine. Then, specifically, the camshaft 2 of the present embodiment is fixed to the vane rotor 14 in a state, where the camshaft 2 coaxially extends through the housing 11 and the vane rotor 14 from a bearing 116 side of the housing 11 in a direction away from the bearing 161.

Specifically, the camshaft 2 is provided with a step portion 163 having a circular ring flange shape at a side of the bearing 161 toward the end portion 162. The step portion 163 is fitted with the sprocket 13 and is rotatable relative to the sprocket 13.

Also, the camshaft 2 is provided with a fitting portion 164, which has a hollow cylindrical shape, at a position between the step portion 163 and the end portion 162. The fitting portion 164 is fitted with the hub portion 14 a of the vane rotor 14 in a state, where the fitting portion 164 is unable to rotate relative to the hub portion 14 a. Also, the fitting portion 164 is fitted with the bottom wall portion of the tubular portion 12 a of the shoe housing 12 via a metal bush 165, which has a hollow cylindrical shape, in a state where the fitting portion 164 is rotatable relative to the bottom wall portion.

Furthermore, the end portion 162 of the camshaft 2 projects from the bottom wall portion of the tubular portion 12 a in the direction away from the bearing 161, and has an external thread 167 on an outer peripheral surface thereof. The external thread 167 is threadably engaged with an internal threaded hole 169 of a threaded member 168 made of a metal nut. The threaded member 168 is mounted on the end portion 162 of the camshaft 2 as above, and the threaded member 168 fastens the vane rotor 14 to the camshaft 2 by holding the hub portion 14 a and the bush 165 between the threaded member 168 and the step portion 163. In other words, the threaded member 168 serves as a fastening member, and the present embodiment employs a general nut-shaped threaded member.

As shown in FIGS. 1, 3, the camshaft 2 defines an axial hole 170 therein. The axial hole 170 is provided to open at an end surface 172 of the end portion 162 of the camshaft 2, and has a cylindrical hole shape with a bottom. The axial hole 170 extends in a longitudinal direction to pass a radial center part of each of the portions 162, 164, 163 of the camshaft 2. Thus, the axial hole 170 has a bottom portion 173 that is positioned away from an end surface 174 of the vane rotor 14 toward the bearing 161. Also, the axial hole 170 is flared or expanded on the opening side thereof to have a step therein. Specifically, the axial hole 170 has an inner diameter on the opening side thereof larger than an inner diameter on the side toward the bearing 161. Thus, the axial hole 170 has a large diameter hole portion 175 and a small diameter hole portion 176 that is positioned on a side of the large diameter hole portion 175 toward the bearing 161.

As shown in FIG. 1, the control valve 100 includes a sleeve 110, a spool 130 and a return spring 140 in addition to the solenoid portion 120.

The metallic sleeve 110 opens in a direction away from the bearing 161 and has a straight hollow cylindrical shape with a bottom. The metallic sleeve 110 has the opening that is attached to the solenoid portion 120. The solenoid portion 120 is mounted on a chain cover 180 of the internal combustion engine, which cover 180 is fixed to the engine head 160 for receiving the drive unit 10. Thus, the sleeve 110 is mounted on the engine head 160, which serves as an immovable part of the internal combustion engine, via the solenoid portion 120 and the chain cover 180 such that the sleeve 110 is immovably provided. It should be noted that the chain cover 180 of present embodiment is provided to open toward the bearing 161 to cover the outer periphery of the housing 11 and the threaded member 168. Also, the chain cover 180 fixedly holds the sleeve 110 at a position on a side of the drive unit 10 opposite from the bearing 161.

The sleeve 110 has an opposite side portion opposite from the solenoid portion 120, and the side portion of the sleeve 110 is coaxially inserted into the axial hole 170 of the camshaft 2. Specifically, the sleeve 110 of the present embodiment is received in the axial hole 170 such that the sleeve 110 is positioned adjacent the bottom portion 173 of the axial hole 170. Thus, the sleeve 110 has a bottom end portion 182 that is positioned on a side of the end surface 174 of the vane rotor 14 toward the bearing 161. In other words, the sleeve 110 extends beyond the end surface 174 of the vane rotor 14 toward the bearing 161 in the axial hole 170. Also, as shown in FIG. 4, the sleeve 110 of the present embodiment defines a radial clearance 184 between (a) a peripheral wall portion 183 of the sleeve 110 and (b) each of the hole portions 175, 176 of the axial hole 170. Because the sleeve 110 has the straight hollow cylindrical shape as above, the clearance 184 defined between the large diameter hole portion 175 and the peripheral wall portion 183 is smaller than the clearance 184 defined between the small diameter hole portion 176 and the peripheral wall portion 183.

As shown in FIG. 1, the radial center part of the bottom end portion 182 of the sleeve 110 is provided with the input port 112 that is communicated with the input passage 80. In the above, the end portion 182 of the sleeve 110 is positioned adjacent the bottom portion 173 of the axial hole 170. The input passage 80 has a bearing passage portion 185 and a camshaft passage portion 186. The bearing passage portion 185 is formed on the bearing 161 and the camshaft passage portion 186 is formed on the camshaft 2. The bearing passage portion 185 is configured to be communicated with the discharge port of the pump 4, and extends to a support boundary surface 187 defined between the bearing 161 and the camshaft 2. Also, as shown in FIGS. 1 and 5, the camshaft passage portion 186 is always communicated with the bearing passage portion 185 at the support boundary surface 187, and opens to the bottom portion 173 of the axial hole 170 such that the camshaft passage portion 186 faces or directly communicates with the input port 112. Due to the above configuration, in the present embodiment, the input passage 80, which extends across the support boundary surface 187, reliably supplies hydraulic oil to the input port 112 from the pump 4, which is communicated with the input port 112 through the bearing 161 and the camshaft 2.

As shown in FIG. 1, the peripheral wall portion 183 of the sleeve 110 has a section that is received in the small diameter hole portion 176, and the above section of the peripheral wall portion 183 is provided with the first drain port 118, the advance output port 114, the retard output port 116, and the second drain port 119, which are arranged in this order in a direction away from the bearing 161.

As shown in FIG. 5, the first drain port 118 is communicated with the drain passage 82 by radially extending through a section of the peripheral wall portion 183, and the above section is positioned on a side of the end surface 174 of the vane rotor 14 toward the bearing 161. In the above configuration, the step portion 163 of the camshaft 2 is positioned on a side of the end surface 174 of the vane rotor 14 toward the bearing 161, and the drain passage 82 extends through the step portion 163 in a direction angled relative to the axial direction of the camshaft 2 as shown in FIG. 5. The drain passage 82 has one end portion that opens at the outer peripheral surface of the step portion 163, and the above outer peripheral surface is covered by the chain cover 180. Also, the drain passage 82 has the other end portion that opens to the small diameter hole portion 176 to be communicated with the first drain port 118. Due to the above, in the present embodiment, hydraulic oil is discharged from the first drain port 118 into the chain cover 180 through the drain passage 82. As above, hydraulic oil is discharged through the first drain port 118 through the drain passage 82 to a space positioned on a side of the end surface 174 of the vane rotor 14. It should be noted that in the present embodiment, the chain cover 180 has an opening portion 189 that is positioned above the oil pan 5, and hydraulic oil is discharged from the cover 180 to the oil pan 5 through the opening portion 189.

As shown in FIGS. 5, 6, the advance output port 114 radially extends through the peripheral wall portion 183 such that the advance output port 114 is communicated with the advance passages 72 to 74. In the above, as shown in FIGS. 3, 5, 6, the advance passages 72 to 74 are configured to radially extend through the fitting portion 164 and the hub portion 14 a. Each of the advance passages 72 to 74 has an end portion opposite from the advance chambers 52 to 54, and each end portion opens to the small diameter hole portion 176 such that the advance passages 72 to 74 are communicated with the advance output port 114. As a result, in the present embodiment, the advance passages 72 to 74 reliably enables hydraulic oil to be circulated between the advance output port 114 and the advance chambers 52 to 54, which are communicated with each other through the camshaft 2 and the vane rotor 14. The above circulation of hydraulic oil includes supply and discharge of hydraulic oil.

As shown in FIGS. 1, 3, the retard output port 116 radially extends through the peripheral wall portion 183 such that the retard output port 116 is communicated with the retard passages 76 to 78. In the above, the retard passages 76 to 78 are configured to radially extend through the fitting portion 164 and the hub portion 14 a. Each of the retard passages 76 to 78 has an end portion opposite from the retard chambers 56 to 58. Each end portion opens to the small diameter hole portion 176 such that the retard passages 76 to 78 are communicated with the retard output port 116. Thus, in the present embodiment, the retard passages 76 to 78 reliably enables hydraulic oil to be circulated between the retard output port 116 and the retard chambers 56 to 58, which are communicated with each other through the camshaft 2 and the vane rotor 14.

As shown in FIG. 1, the second drain port 119 radially extends through the peripheral wall portion 183 such that the second drain port 119 is communicated with the drain passage 83 that is defined at the camshaft 2 between the large diameter hole portion 175 and the peripheral wall portion 183. Due to the above, in the present embodiment, hydraulic oil is discharged from the second drain port 119 into the chain cover 180 through the drain passage 83, and thereby the hydraulic oil is able to be discharged from the chain cover 180 to the oil pan 5.

Multiple annular sealing members 188, which are made of a rubber resin or a resin to have circular ring shapes, are arranged at the peripheral wall portion 183 of the sleeve 110 and are fitted with the outer peripheral surface of the peripheral wall portion 183. As shown in FIG. 4, in the present embodiment, one of the annular sealing members 188 is provided at a position between the bottom end portion 182 defining the input port 112 therein and the first drain port 118. The other one of the annular sealing members 188 is provided at a position between the first drain port 118 and the advance output port 114. Still the other one of the annular sealing members 188 is provided at a position between the advance output port 114 and the retard output port 116. Also, further the other one of the annular sealing members 188 is provided at a position between the retard output port 116 and the second drain port 119, respectively. Each of the annular sealing members 188 has an outer peripheral surface that slides on an inner peripheral surface of the small diameter hole portion 176 of the axial hole 170. Thus, the annular sealing members 188 seal between the ports 112, 114, 116, 118, 119 and keeps the clearance 184 defined between the small diameter hole portion 176 and the peripheral wall portion 183.

As shown in FIG. 1, the metal spool 130 has a column shape with multiple lands provided thereon, and is coaxially received in the sleeve 110. Also, the metal spool 130 is slidable relative to the peripheral wall portion 183. The spool 130 moves coaxially together with a drive shaft (not shown), which is actuated by the solenoid portion 120, and the spool 130 has an end surface 190 that faces the input port 112 defined at the bottom end portion 182 of the sleeve 110. As above, the end surface 190 of the spool 130 is positioned away from the solenoid portion 120. In other words, the end surface 190 is provided on a side of the spool 130 toward the bearing 161.

As shown in FIG. 4, the spool 130 includes an advance support land 191, an advance switch land 192, a retard switch land 193, and a retard support land 194, which are arranged in the above order in a direction away from the bearing 161.

The advance support land 191 is always slidably supported by a section of the peripheral wall portion 183, and the above section is positioned on a side of the first drain port 118 toward the bearing 161. The advance switch land 192 is slidably supported by one of other sections of the peripheral wall portion 183, and the sections are provided on both axial sides of the advance output port 114. In other words, the other sections of the peripheral wall portion 183 are provided on sides of the advance output port 114 toward the first drain port 118 and the retard output port 116, respectively, such that the other sections have the advance output port 114 therebetween in the longitudinal direction of the spool 130. The spool 130 defines an inner passage 197 therein. Specifically, the inner passage 197 opens at a radial center part of the end surface 190 to be communicated with the input port 112 as shown in FIG. 4. As shown in FIGS. 3, 4, 6, the inner passage 197 radially outwardly opens to be communicated with an aperture 196 defined between the advance switch land 192 and the retard switch land 193.

Therefore, as shown in FIG. 7, when the advance switch land 192 is supported only by a section of the peripheral wall portion 183, the advance output port 114 is communicated with the input port 112 through the inner passage 197. In the above, the section of the peripheral wall portion 183 is provided on a side of the advance output port 114 toward the first drain port 118. Also, as shown in FIG. 4, when the advance switch land 192 is supported only by the other section of the peripheral wall portion 183, the advance output port 114 is communicated with the first drain port 118 through an aperture 198 defined between the advance support land 191 and the advance switch land 192. In the above, the other section of the peripheral wall portion 183 is away from the advance output port 114 toward the retard output port 116. Further, as shown in FIG. 8, when the advance switch land 192 is supported by both of the above sections located on both axial sides of the advance output port 114, the advance output port 114 is discommunicated from other ports.

As shown in FIG. 4, the retard support land 194 is always slidably supported by a section of the peripheral wall portion 183, and the section is positioned on a side of the second drain port 119 toward the solenoid portion 120 (or in a direction away from the bearing 161). The retard switch land 193 is slidably supported by at least one of other sections of the peripheral wall portion 183. In the above, the other sections are positioned on both axial sides of the retard output port 116. In other words, each of the other sections of the peripheral wall portion 183 is positioned on a side of the retard output port 116 toward the second drain port 119 or toward the advance output port 114.

Therefore, as shown in FIG. 4, when the retard switch land 193 is supported only by the section of the peripheral wall portion 183, the retard output port 116 is communicated with the input port 112 through the inner passage 197. In the above, the section is positioned on a side of the retard output port 116 toward the second drain port 119. Also, as shown in FIG. 7, when the retard switch land 193 is supported only by the other section of the peripheral wall portion 183, the retard output port 116 is communicated with the second drain port 119 through an aperture 199 defined between the retard switch land 193 and the retard support land 194. In the above, the section is positioned on a side of the retard output port 116 toward the advance output port 114. Furthermore, as shown in FIG. 8, when the retard switch land 193 is supported by both of the above sections of the peripheral wall portion 183, the retard output port 116 is discommunicated from other ports. In the above, the sections are located on both axial sides of the retard output port 116 toward the second drain port 119 and toward the advance output port 114.

As shown in FIG. 4, the return spring 140 is made of a metal compression coil spring, and is coaxially received in the sleeve 110. The return spring 140 is held between the bottom end portion 182 of the sleeve 110 and the advance support land 191 of the spool 130. The return spring 140 is compressed and deformed to generate a restoring force that biases the spool 130 in a longitudinal direction toward the solenoid portion 120 (or in other words, in a direction away from the bearing 161). In contrast, the solenoid portion 120 is energized to generate an electromagnetic driving force that biases the spool 130 in the longitudinal direction toward the return spring 140 (or in other words, in a direction toward the bearing 161), As a result, in the control valve 100, the spool 130 is actuated or displaced based on a balance between the restoring force generated by the return spring 140 and the electromagnetic driving force generated by the solenoid portion 120.

(Characteristic Operation)

Characteristic operation of the present embodiment will be detailed below.

During an operation of the internal combustion engine, in which the pump 4 is driven, the control circuit 150 computes an actual engine phase and a target engine phase of the camshaft 2 relative to the crankshaft, and the control circuit 150 controls energization current to the solenoid portion 120 of the control valve 100 based on the computation result. Thus, the spool 130 of the control valve 100 is displaced, and an amount of hydraulic oil accordingly to the displacement position of the spool 130 is supplied to and discharged from the advance chambers 52 to 54 and the retard chambers 56 to 58. As a result, valve timing is adjusted. An valve timing adjustment operation according to the valve timing adjusting apparatus 1 of the present embodiment will be described.

(1) Retard Operation

A retard operation for retarding valve timing, in which the engine phase of the camshaft 2 relative to the crankshaft is changed in the retard direction such that valve timing is retarded, will be described.

When an operational condition of the internal combustion engine, which indicates an idling operation or a high load and high speed operational state, is established, the control circuit 150 controls a value of the energization current for energizing the solenoid portion 120 smaller than a reference value lb. As a result, the restoring force of the return spring 140 displaces the spool 130 to the retard position shown in FIG. 4 such that the retard output port 116 is made communicated with the input port 112. Also, the advance output port 114 is made communicated with the first drain port 118.

As a result, the discharge oil from the pump 4 to the input passage 80 is supplied to the retard chambers 56 to 58 through the input port 112, the retard output port 116, and the retard passages 76 to 78. Also, hydraulic oil in the advance chambers 52 to 54 is discharged to the oil pan 5 through the advance passages 72 to 74, the advance output port 114, the first drain port 118, and the drain passage 82. As a result, valve timing is made quickly retarded.

(2) Advance Operation

An advance operation for advancing valve timing, in which the engine phase of the camshaft 2 relative to the crankshaft is changed in the advance direction such that the valve timing is advanced, will be described.

When an operational condition of the internal combustion engine, which indicates a low/medium speed and medium load state that requires a sufficient output torque for the vehicle, is established, the control circuit 150 controls the value of the energization current for energizing the solenoid portion 120 to be greater than the predetermined reference value I_(b). Then, the electromagnetic driving force of the solenoid portion 120 displaces the spool 130 to the advance position shown in FIG. 7, and thereby the advance output port 114 is made communicated with the input port 112, and the retard output port 116 is made communicated with the second drain port 119.

As a result, discharge oil from the pump 4 to the input passage 80 is supplied to the advance chambers 52 to 54 through the input port 112, the advance output port 114, and the advance passages 72 to 74. Also, hydraulic oil in the retard chambers 56 to 58 is discharged to the oil pan 5 through the retard passages 76 to 78, the retard output port 116, the second drain port 119, and the drain passage 83. As a result, valve timing is made quickly advanced.

(3) Retention Operation

An retention operation for retaining valve timing, in which the engine phase is retained at a predetermined target phase region such that the valve timing is for substantially retained, will be described.

When the operational condition of the internal combustion engine, which indicates a stable operational state, such as a state for holding an accelerator pedal of the vehicle at a position, is established, the control circuit 150 controls the value of the energization current for energizing the solenoid portion 120 to be the reference value I_(b). As a result, the balance between the electromagnetic driving force of the solenoid portion 120 and the restoring force of the return spring 140 displaces the spool 130 to the retention position shown in FIG. 8, and thereby the advance output port 114 and the retard output port 116 are discommunicated from any of the input port 112, the first drain port 118, and the second drain port 119.

As a result, discharge oil from the pump 4 to the input passage 80 is disabled to be supplied to any of the advance chambers 52 to 54 and the retard chambers 56 to 58. Also, hydraulic oil in the advance chambers 52 to 54 and hydraulic oil in the retard chambers 56 to 58 are disabled to be discharged therefrom. As a result, the valve timing is made substantially retained.

In the present embodiment, the sleeve 110 of the control valve 100 is coaxially received in the axial hole 170, which opens at the end surface of the camshaft 2 that extending through the vane rotor 14. The above end surface of the camshaft 2 is positioned away from the bearing 161. As a result, the length of the sleeve 110 is not limited by the specification of the apparatus 1. Therefore, in the control valve 100, the length of the sleeve 110 is flexibly set in order to sufficiently secure the length of a sealing part for sealing the slide boundary surfaces between the sleeve 110 and the spool 130.

In the present embodiment, the sleeve 110 extends inside the axial hole 170 and projects away from the end surface 174 of the vane rotor 14 toward the bearing 161. In the above, the end surface 174 of the vane rotor 14 faces toward the bearing 161. Due to the above, the long sleeve 110, which projects away from the end surface 174 of the vane rotor 14 toward the bearing 161, is usable without the limitation of the thickness of the vane rotor 14, and thereby a sufficient sealing length for sealing the slide boundary surfaces between the sleeve 110 and the spool 130 is attained such that the adjustment responsivity of valve timing is reliably improved.

In the above first embodiment, a dimension of the axial hole 170, which is formed in the long camshaft 2, is limited from being regulated or influenced by a specification of the apparatus 1, such as thickness of the vane rotor 14. Therefore, in the first embodiment, the axial hole 170 having the bottom is formed to extend from the end surface 172 of the camshaft 2, which is opposite from the bearing 161, and to extend beyond the end surface 174 of the vane rotor 14 toward the bearing 161. In the above, the end surface 174 faces in a direction toward the bearing 161. Thus: the long sleeve 110, which is received in the hole 170 to reach the vicinity of the bottom portion 173 of the hole 170, is able to be used. As a result, according to the first embodiment, in the control valve 100, a length of the sealing part for sealing the slide boundary surfaces defined between (a) the peripheral wall portion 183 of the sleeve 110 and (b) each of lands 191 to 194 of the spool 130 is sufficiently attained. Accordingly, leakage of hydraulic oil through the slide boundary surfaces is limited, and thereby control responsivity of the control valve 100 is effectively improved.

In the apparatus of JP-A-2006-63835, working fluid is outputted from the advance output port to the advance chamber through the bearing and the camshaft, and also, another route through the bearing and the camshaft allows working fluid to be outputted from the retard output port to the retard chamber. Thus, above two output routes for outputting working fluid extend across the support boundary surfaces between the bearing and the camshaft, and thereby working fluid may leak through the support boundary surfaces. As a result, the adjustment responsivity of valve timing may deteriorate.

In contrast, according to the first embodiment, the input route for inputting hydraulic oil to the input port 112 of the control valve 100 across the support boundary surface 187 defined between the bearing 161 and the camshaft 2 employs only one input passage 80. Thus, leakage of hydraulic oil through the boundary surface 187 is limited. Due to the above, hydraulic oil, which is to be supplied to the advance chambers 52 to 54 or the retard chambers 56 to 58, is limited from becoming in short due to the leakage. Also, the adjustment responsivity of valve timing improved by the axial hole 170 of the camshaft 2 is limited from being degraded due to the leakage of working fluid.

Further, according to the first embodiment, because the clearance 184 is defined in the radial direction between the peripheral wall portion 183 of the sleeve 110 and the axial hole 170 of the camshaft 2, the interference between the sleeve 110 and the axial hole 170 is limited. Due to the above, the spool 130 is limited from being displaced due to the position displacement of the sleeve 110 caused by the interference with the axial hole 170. Also, the camshaft 2 is limited from being subjected to the drag force in the rotational direction due to the interference of the sleeve 110 to the axial hole 170.

Also, according to the first embodiment, the multiple annular sealing members 188, which are provided between the sleeve 110 and the axial hole 170, seal the gaps between the adjacent ports among the ports 112, 118, 114, 116, 119. As a result, flow of hydraulic oil between the adjacent ports through the clearance 184 defined between the sleeve 110 and the axial hole 170, which flow may otherwise deteriorate the control responsivity of the control valve 100, is limited. Also, each of the annular sealing members 188 is capable of compensating the tilt of the axial hole 170 relative to the sleeve 110 and the axial displacement of the axial hole 170 relative to the sleeve 110 by a self aligning effect. Thereby, the interference between the sleeve 110 and the axial hole 170 is more limited from occurring.

As above, in the first embodiment, specifically, in the advance operation and the retard operation, a relative rotational speed of the vane rotor 14 relative to the housing 11, which rotor 14 rotates with the camshaft 2, is reliably increased. Therefore, according to the first embodiment, high adjustment responsivity for adjusting the valve timing is achieved.

In addition to the above, according to the first embodiment, in the camshaft 2, the hub portion 14 a is held between the threaded member 168 and the step portion 163. In the above, the threaded member 168 is mounted on the end portion 162 of the camshaft 2 opposite from the bearing 161, and the step portion 163 is provided on a side of the threaded member 168 of the camshaft 2 toward the bearing 161. As above, the hub portion 14 a fastens the vane rotor 14 to the camshaft 2. Accordingly, in the first embodiment, the end portion 162 of the camshaft 2 is made closer to the step portion 163 such that an extension dimension of the camshaft 2 in a direction away from the bearing 161 is sufficiently made shorter. Also, the sleeve 110 of the control valve 100 is received in the axial hole 170. As a result, the size of the apparatus 1 in the longitudinal direction is reduced. Therefore, according to the first embodiment, the apparatus 1 including the control valve 100 has a smaller mounting space.

Second Embodiment

As shown in FIG. 10, the second embodiment of the present invention is a modification of the first embodiment. The second embodiment is characterized in that a check valve 200 is provided in the inner passage 197 of the spool 130.

Specifically, the check valve 200 includes a valve seat 202, a valve member 204 and a biasing member 206. The valve seat 202 is a radially inner surface formed on an intermediate position of the inner passage 197, and an inner diameter of the valve seat 202 is reduced toward the input port 112 to have a conic surface. The valve member 204 is made of a metal to have a bulbous shape, and is provided in the inner passage 197 on an opposite side of the valve seat 202 opposite from the input port 112. Thus, the valve member 204 is able to be displaceable in the longitudinal direction so that the valve member 204 is positioned away from and is seated on the valve seat 202. The biasing member 206 is made of a metallic compression coil spring, and is provided in the inner passage 197 between an internal wall surface 208 and the valve member 204. The internal wall surface 208 faces the valve seat 202 in the longitudinal direction. The biasing member 206 is compressed and deformed such that the biasing member 206 generates a restoring force that biases the valve member 204 toward the valve seat 202.

Thus, pressure of hydraulic oil that flows into the input port 112 displaces the valve member 204 away from the valve seat 202 against the restoring force of the biasing member 206 as shown in FIG. 11. Thus, when the check valve 200 is opened as above or the check valve 200 opens the inner passage 197, hydraulic oil is allowed to flow through the input port 112 to the aperture 196 of the spool 130. In contrast, when pressure of hydraulic oil, which flows into the aperture 196, and the restoring force of the biasing member 206 cause the valve member 204 to be seated on the valve seat 202, and thereby the check valve 200 is closed as shown in FIG. 10, hydraulic oil is limited from flowing from the aperture 196 toward the input port 112 (or in other words, toward the bearing 161).

In the above retard operation of the second embodiment, when a variable torque of the camshaft 2 is applied to the vane rotor 14 in the advance direction relative to the housing 11, the vane rotor 14 compresses hydraulic oil in the retard chambers 56 to 58, and thereby hydraulic oil in the retard chambers 56 to 58 is caused to flow back to the retard output port 116 through the retard passages 76 to 78. However, the back flow of hydraulic oil from the retard output port 116 to the input port 112 through the aperture 196 and the inner passage 197 is regulated by the check valve 200 because the pressure of hydraulic oil of the back flow is higher than pressure of the discharge oil of the pump 4. It should be noted that in the retard operation, when the variable torque of the camshaft 2 is applied to the vane rotor 14 in the retard direction relative to the housing 11, pressure of discharge oil of the pump 4 opens the check valve 200. Thereby, hydraulic oil is reliably supplied to the retard chamber 56 to 8.

Also, in the advance operation, when the variable torque of the camshaft 2 is applied to the vane rotor 14 in the retard direction relative to the housing 11, the vane rotor 14 compresses hydraulic oil in the advance chambers 52 to 54, and thereby the hydraulic oil in the advance chambers 52 to 54 is caused to flow back to the advance output port 114 through the advance passages 72 to 74. However, the back flow of hydraulic oil from the advance output port 114 to the input port 112 through the aperture 196 and the inner passage 197 is regulated by the check valve 200 because the pressure of hydraulic oil of the back flow is higher than pressure of discharge oil of the pump 4. It should be noted that in the advance operation, when the variable torque of the camshaft 2 is applied to the vane rotor 14 in the advance direction relative to the housing 11, a force of pressure of discharge oil of the pump 4 opens the check valve 200, and thereby hydraulic oil is reliably supplied to the advance chambers 52 to 54.

In the above second embodiment, because hydraulic oil is limited from flowing from one of (a) the advance chambers 52 to 54 and (b) the retard chambers 56 to 58, to which the hydraulic oil is to be supplied, deterioration of the adjustment responsivity of valve timing caused by the back flow is effectively limited In the present embodiment, the check valve 200 is provided inside the inner passage 197, which is provided inside the spool 130, and which is communicated with the input port 112. As a result, the camshaft 2 is not required to have a space therein for mounting the check valve 200.

Other Embodiment

As above, multiple embodiments of the present invention are described. However, the present invention is not limited to the above embodiments and is applicable to various other embodiments provided that the embodiment is not deviating from the gist of the present invention.

Specifically, in the embodiment, the relation between “timing advance” and “timing retard” is interchangeable with each other differently from the relation in the above description.

The control valve 100 may employ, for example, a piezoactuator or an oil pressure actuator for driving the spool 130 in place of the above solenoid portion 120 that drives the spool 130 in the above embodiments.

The “fastening member” employs the threaded member 168 that is threadably engaged with the camshaft 2. However, alternatively, the “fastening member” may employ, for example, a fitting member, which is fitted with the camshaft 2, and which is threadably fixed to the camshaft 2 through another member.

In the above embodiment, a cover member, such as the chain cover 180 for receiving the drive unit 10, is provided between the sleeve 110 and the immovable part in order to mount the sleeve 110 to the immovable part for fixation, such as the engine head 160. However, for example, a stay, which stretches over the periphery or a radially outer side of the drive unit 10, may be alternatively employed.

In the above embodiments, the mechanical pump 4, which is mechanically driven by the internal combustion engine, serves as a fluid supply source for supplying hydraulic oil. However, an electric pump, which is driven by the energization along with the operation of the internal combustion engine, may be alternatively employed, for example.

In the above embodiments, the present invention is applied to the apparatus that adjusts valve timing of the intake valve. However, the present invention may be alternatively applied to an apparatus that adjusts valve timing of an exhaust valve that serves as a “valve”, and may be alternatively applied to an apparatus that adjusts valve timing of both the intake valve and the exhaust valve.

Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader terms is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described. 

1. A valve timing adjusting apparatus for an internal combustion engine having a bearing, wherein the valve timing adjusting apparatus adjusts valve timing of a valve based on torque transmitted from a crankshaft, the valve timing adjusting apparatus comprising: a camshaft that is supported by the bearing of the internal combustion engine, wherein: the camshaft opens and closes the valve based on the torque transmitted from the crankshaft; the camshaft has an end portion that extends in an axial direction from the bearing; the camshaft includes a step portion on a side of the bearing toward the end portion of the camshaft; and the camshaft defines an axial hole therein that opens at an end surface of the end portion of the camshaft; a housing that is rotatable synchronously with the crankshaft; a vane rotor that is rotatable synchronously with the camshaft, which extends through the vane rotor, wherein: the vane rotor defines an advance chamber and a retard chamber in the housing; the vane rotor is rotatable relative to the housing in an advance direction when working fluid is supplied to the advance chamber; and the vane rotor is rotatable relative to the housing in a retard direction when working fluid is supplied to the retard chamber; a control valve that is received in the axial hole of the camshaft and includes a spool and a sleeve, wherein: the spool is slidably received in the sleeve; the sleeve is coaxially received in the axial hole and is stationarily provided; the sleeve includes: an input port, through which working fluid flows into the sleeve; an advance output port, through which working fluid flows into the advance chamber; and a retard output port, through which working fluid flows into the retard chamber; and the control valve displaces the spool to control communication between the input port and the advance output port and to control communication between the input port and the retard output port; and a fastening member that is mounted on the end portion of the camshaft on a side of the vane rotor opposite from the bearing and the step portion, wherein: the vane rotor is coaxially fastened to the camshaft in a state, where the vane rotor is held between the fastening member and the step portion; working fluid flows into the input port through the camshaft; and each of the advance output port and the retard output port is communicated with a corresponding one of the advance chamber and the retard chamber through the camshaft.
 2. The valve timing adjusting apparatus according to claim 1, wherein: the camshaft defines a camshaft passage therein that is communicated with the input port such that working fluid flows through the camshaft passage into the input port; the camshaft further includes a plurality of passages therein; and each of the advance output port and the retard output port is communicated with a corresponding one of the advance chamber and the retard chamber through a corresponding one of the plurality of passages of the camshaft.
 3. The valve timing adjusting apparatus according to claim 1, wherein: the vane rotor has an end surface that faces toward the bearing; and the sleeve extends beyond the end surface of the vane rotor toward the bearing in the axial hole.
 4. The valve timing adjusting apparatus according to claim 1, wherein: the input port receives working fluid through the bearing and the camshaft.
 5. The valve timing adjusting apparatus according to claim 4, wherein: the bearing defines a bearing passage therein; the camshaft defines a camshaft passage therein that is communicated with the input port; and the input port receives working fluid through the bearing passage of the bearing and the camshaft passage of the camshaft.
 6. The valve timing adjusting apparatus according to claim 1, wherein: the vane rotor has an end surface that faces toward the bearing; the sleeve includes: a first drain port that is communicated through the camshaft to a first space positioned on a side of the end surface of the vane rotor toward the bearing, the working fluid being discharged to the first space through the first drain port and the camshaft; and a second drain port that is communicated through the camshaft to a second space positioned on a side of the end portion of the camshaft opposite from the bearing, the working fluid being discharged to the second space through the second drain port and the camshaft; the control valve displaces the spool to control communication between the input port and each of the advance output port and the retard output port, and to control communication between (a) each of the advance output port and the retard output port and (b) a corresponding one of the first drain port and the second drain port; the vane rotor is rotated relative to the housing in the advance direction when the followings are satisfied: working fluid is supplied to the advance chamber; and working fluid is discharged from the retard chamber; and the vane rotor is rotated relative to the housing in the retard direction when the followings are satisfied: working fluid is supplied to the retard chamber; and working fluid is discharged from the advance chamber.
 7. The valve timing adjusting apparatus according to claim 6, wherein: the camshaft defines a first drain passage and a second drain passage therein; working fluid is discharged to the first space through the first drain port and the first drain passage; and working fluid is discharged to the second space through the second drain port and the second drain passage.
 8. The valve timing adjusting apparatus according to claim 1, wherein: the sleeve and the axial hole define therebetween a clearance in a radial direction.
 9. The valve timing adjusting apparatus according to claim 8, further comprising: an annular sealing member that is mounted on an outer peripheral surface of the sleeve such that the annular sealing member is slidable with the axial hole, wherein the annular sealing member seals between the input port, the advance output port, and the retard output port of the sleeve.
 10. The valve timing adjusting apparatus according to claim 1, further comprising: a check valve that is provided on a side of the bearing toward the spool, wherein: the check valve allows working fluid to flow in a direction from the bearing toward the spool; and the check valve limits working fluid from flowing in a direction from the spool toward the bearing.
 11. The valve timing adjusting apparatus according to claim 10, wherein: the spool defines therein an inner passage that is communicated with the input port; and the check valve is provided inside the inner passage.
 12. The valve timing adjusting apparatus according to claim 1, wherein: the fastening member is a threaded member that defines an internal threaded hole therein; and the internal threaded hole is threadably engaged with the end portion of the camshaft. 